The present invention relates to a method for connecting a telephone network and an IP network (internet protocol network), a method for detecting faults and a method for controlling alternative routing.
Particularly, the present invention relates to a method for connecting a telephone network and an IP network in an internet gateway system constituted by a signaling gateway/media gateway controller and a gateway device, the method detecting a fault at an IP network interface of the gateway device, blocking the line to the upstream telephone network and instructing alternative routing.
Presently available measures to detect a fault between nodes of a telephone network include monitoring of the state of a common line signal link between opposite at an interface between networks, monitoring of frame bits of a communication line and monitoring of the state of a circuit between a network and a user terminal at a user/network interface. Referring to presently available measures to notify each of nodes forming a network of a fault or congestion of traffic and to instruct it on alternative routing, a fault of a common line signal can be notified and an instruction can be made on alternative routing utilizing a message transfer part (MTP) of a common channel signaling #7 (CCS7) at an interface between networks; blocking of a communication line can be instructed utilizing a blocking signal in an ISDN user part (ISUP); and an instruction on alternative routing can be made using a redirection procedure according to the TTC (Telecommunication Technology Committee) specifications or using a pivot procedure according to the ITU-T (International Telecommunication Union) recommendations and TTC specifications.
Referring to user/network interfaces, there is no measure to allow a user apparatus including a gateway device for an IP network to notify of a telephone network of a fault and to instruct alternative routing, and alternative routing is performed by the network by means of line state monitoring and incoming call transfer. As another measure to allow alternative routing, when an incoming call number is converted at a service control point (SCP) in an IN (Intelligent Network Internetwork Interface) procedure, control may be performed to provide an effect equivalent to alternative routing by switching the converted number depending on the state of the network.
Measures to detect a fault between nodes of an IP network include a method in which congestion of traffic or a fault between opposite nodes is detected by exchanging a message such as “ping” according to the ICMP (Internet Control Message Protocol) defined in the RFC (Requests for Comments) of the IETF (Internet Engineering Task Force) between the opposite nodes and a method in which the state of the apparatus at each of nodes forming a network is collected using a network manager such as an SNMP (Simple Network Management Protocol) manager or gate keeper defined in the RFC1157. Referring to the method for notifying a fault or congestion of traffic and instructing alternative routing, a method is used in which routing information is distributed to each of nodes forming a network using a router or a network manager such as an SNMP manager or gate keeper according to a dynamic routing protocol such as the RIP (Routing Information Protocol) defined in the RFC2453, the OSPF (Open Shortest Path Fast) defined I the RFC2328 or the BGP (Border Gateway Protocol) defined in the RFC1771.